Hi glad to be here I have a 1980 T/A with an 88 tpi on a L31 motor car was running great until one night it started sputtering at part throttle but was ok with half or more went through all the basics and couldn’t find the problem since then it has gotten worse. I have already replaced the fuel pump filter mass air meter temp sensor tps ecu complete distributor and now even new injectors because when I would prime the pump fuel pressure would go to about 45 and quickly drop off so I put the injectors in tonight and it was holding pressure. But now the car runs even worse. The motor is new less than 1000 miles. I have worked on these engines since I was 16 now 51 and have never had an issue like this before I am literally at my wits end and ideas would be greatly appreciated

 

Does it do that right from startup, or does the engine have to warm some first?

 

it does it from startup but it sputters worse as it gets warm I’m actually putting the old injectors back in right now what I did is pull the fuel rail up to see if any of the injectors are leaking and they are not either is the cold start but I’m still losing pressure and I had another new regulator here swapped that out also and still bleeding back only thing that I didn’t mention is when you get off the throttle I get exhaust back fires which is telling me I have unspent fuel

 

What makes you think it's a fuel system problem? Have you verified ignition system is good? Why are you putting the old injectors back in, Have you got a datalog you can post?

 

I have replaced everything in the ignition system twice and or 3 times I don’t have a data log cause my snap on brick took a crap on me my plugs are clean but it sounds like it’s loading up. I’m putting the old injectors back in cause it’s worse and pig rich with the new ones.

 

UPDATE I believe that I found the issue but don’t know what would cause it other than maybe the temp sensor when I put it back together late evening and it was idling correctly with the original injectors I had in I went around finger testing each one to feel tapping including the cold start to find that at any temp the engine was at the cold start was working disconnected the clip and then engine is not sputtering anymore took it for a 20 mile ride and it is making power no sputtering. So with that being said what else would cause the cold start injector to continue to work the whole time?

 

The cold start system on the early TPI cars is completely independent of the ECU, it uses some sort of temp switch to control it if i remember correctly. It's probably worse with the new injectors because unless they are exactly the same brand and flow as your old ones you will need to modify the tune to make them work correctly.

 

well the car runs great with it disconnected I just had a hard time starting this morning

 

'89 years the CSI was eliminated and a chip swap could be a solution to disabling the CSI...or take a look at this schematic. Could simply be the thermo/timer is not working...

 

cool thanks for the schematic I figured it had something to do with one of the temp sensors I’m glad I found the issue now to fix the problem which might just be the temp sensor even though I replaced everything on the motor before I put it in last year but parts aren’t made like they used to